Multibreak electric switch



C. D. AINSWORTH MULTIBREAK ELECTRIC SWITCH Filed Sept. 30, 1929 Nov. 1,1932.

Patented Nov. 1, 1932 UNITED STATES PATENT OFFICE CHESTER D. AINSWORTH,OF WOLLASTON, MASSACHUSETTS, ASSIG-NOR TO CONDIT ELEC- TRICALMANUFACTURING CORPORATION, OF SOUTH BOSTON, MASSACHUSETTS, A

CORPORATION OF MASSACHUSETTS MULTIBREAK ELECTRIC SWITCH Applicationfiled September 30, 1929.

This invention relates to alternating electric switches and circuitinterrupters especially adapted to control relatively high potentialalternating current circuits.

In my copending application Serial No. 322,730, filed November 30, 1928,I have described a switch having so many seriallyconnected points ofcircuit interruption that, for the normal line potentiah'the potentialacross any point of interruption cannot eX- ceed theinstantaneously-recovered dielectric strength of thecircuit-interrupting medium. Thus the alternating current arc cannot bere-established after it has gone out at the end of the first currentZero, and the circuit becomes completely opened.

The instantaneously recovered dielectric strength of the medium betweena pair of separable contact members, when air is the insulating medium,is around two hundred volts. Consequently, when a switch of this type isdesigned for use on high voltage circuits the number of sets ofseparable contact members, or points of circuit interruption that are inseries, is considerable. Consequently, the contact resistance betweenthe sum of the contact resistances of the sets of contact members can beconsiderable, especially when the contact members are not in first classcondition, so that it is possible for an arc to be drawn between themain current carrying members of the switch when they separate eventhough the shunting sets of contact or arcing members are engaged. Oneof the main contact carrying members of the switch usually includes alaminated or brush member. It is not advisable to draw an are from thebrush member as the laminations are thin and are liable to be burned byan arc. Consequently, an object of the present invention is theprovision of an alternating current switch having separable main currentcarrying members and a plurality of auxiliary contact members that areconnected in series with each other and in shunt with the main currentcarrying members, combined with other, or tertiary, contact members thatnormally shunt the auxiliary contact members and thus eliminate theircontact resistance especially at the Serial No. 396,195.

time the main current carrying members separate.

Due to the fact that the sum of the contact resistances of the auxiliarycontact members can be considerable, it is not considered advisable tointerpose these contact resistances simultaneously in the switch circuitby the operation of the tertiary set of contact members as an undesiredarc can be drawn therebetween. Consequently, it is a further object ofthe invention to provide the switch with means whereby the sets ofauxiliary arcing members are progressively included in series with eachother in the opening operation of the switch and preferably also areprogressively shunted out of the circuit in the closing operation of theswitch.

A further object of the invention is the provision of shunting means forthe sets of auxiliary contact members adapted to shunt and also unshuntthe auxiliary contact members with a. relatively small amount ofmovement of the main switch operating member so that the switch need nothave an unduly large amount of movement in operating.

A further object of the invention is the provision of a high tensionswitch having a plurality of sets of serially-connected sets ofseparable contact members and associated mechanism so arranged that alarge number of sets of contact members can be installed in a smallspace.

A further object of the invention is generally to improve theconstruction and operation of electric switches.

Fig. 1 is a side elevation illustrating more or less diagrammaticallythe structure of the switch embodying the present invention, the switchbeing open.

F ig. 2 is similar to Fig. 1, except that the switch is closed.

Fig. 3 is a section taken along line 3-3 of Fig. 1.

As here shown, the switch embodying the present invention includes aninsulating frame having horizontal top and bottom bars and 12 and theintermediate vertical connecting bar 14 which also is preferably ofinsulating material. The frame also has vertical insulating bars 16 and18 which are 10- arately with the stationary main current carryingmembers 24 and thus to the alternating current circuit illustrated bythe leads 26. Vertical insulating bars 28 are extendedbetween the endsof the top and bottom bars 10 and 12 and are movable horizontally towardand away from each other by appropriate mechanism and are guided forsuch movement by pins 30 which are carried by said top and bottom barsand are located in horizontal slots 32 in said bars 28. Said bars 28carry a plurality of movable contact members 34 which are here shown ascylindrical in form and are adapted to be moved between and in contactwith the stationary contact members 20 thereby to bridge them. Saidcontact members 34'and 20 constitute the auxiliary contact members ofthe switch and are normally in shunt with the stationary'main currentcarrying members 24when the switch is closed. Said contact members arecaused to be engaged and separated by means of upper and lower levers 36which are pivoted in the middle thereof on pins :38 that are carried bythe intermediate Vertical bar 14.

The ends of said levers are pivotally connected by links 40 to'the upperand lower ends of the contact bars 28. Said levers are reciprocated oroscillated between switch open and closed positions by a verticallyextended operating rod 42 which is pivoted at 44 to the pivotal junctionbetween said levers and one set of links 40 Thus by lowering said rod42, the bars 28 are moved inwardly toward each other and are caused tomove their contact members 34 into engaging position with the stationarycontact members 20. A movement of said rod 42 in the'reverse directiongttects the separation of the contact memers.

In accordance with'this invention, means are provided to exclude thecontact resistance of the contact members from the auxiliary circuitaround the main current carrying members when the switch is closed andto progressively exclude such contact resistance in the closingoperation of the switch and to progressively include such contactresistance in the opening movement of the switch. Said means includesthe rockers 46 which are composed. of conducting material and haveserrated or toothed outer faces 48 which rock in engagement with thecontact blocks '20, the teeth 48 meshing with the contact blocks.

Mechanism is provided whereby the rockers are tilted from one end of thecontact blocks to the other in switch opening and tions 58 between saidlevers and links.

closing operations of the switch, and also are held in contact with saidblocks. Said mechanism includes the set of upper and lower levers 50which are pivoted on pins 52 that are carried by the intermediatevertical bars 14 between the upper and lower levers 36. Said levers 50are pivotally connected to links 54 that in turn are pivotally connectedrespectively to'the top and'bottom ends of the'rockers 46. A verticaloperating rod 56 is pivotally connected to the pivotal com igfie leversand links constitute toggles and the arrangement is such that when onetoggle is being moved to straighten its members, the other toggleisbeing moved-away from a straight condition. Thus the rockers '48 arecaused to rock'from one'end to the other of the contact blocks 20.Therockers are electrically connectedby suitable means as the flexibleconductor 60. Consequently, when the rockers are in engagement with theuppermost contact blocks 20, they shunt the lower contact blocks andtherebyexclude the contact resistances 'therebetween from the auxiliarycircuit around the main current carrying members of-the switch."When-the rockers are in engagement with the lowermost contact blocksthey servetoconnect the two stacks of blocks in series.

thus constitute tertiary contact members that progressively introduceor: cut out the auxilthat engages and raises and lowers the bar '56foroperating the rockers and a second cam groove 66 that engages andoperates the bar '42 for operating the auxiliary contact members. Thecam'grooves'64and 66 are so arranged that the rod 56 is-operated firstand is then held stationary while the rod 42 is operated. The rod 56carries or has 'movable' therewith a bridging 'member '68 which isadapted tobridge themain current carrying members 24 when the switch isclosed and thereby shunt the aforesaid contact members and rockers.

As thus arranged, when the switch is opened, the bridging member'68 isfirst operated to open the'main current'p'ath ofthe switch. The rockers48 are next operated to introduce the sets of auxiliary contact membersin a progressive manner in the switch circuit. The movable auxiliarycontact members 34 are then operated to'separate them from engagementwith the'fixed contact members 20 thereby to interpose a large number ofpoints of interruption in series with the circuit. The closing operationof the switch'is the-reverse of the opening operation. Inthis manner thecontact The rockers resistance of the sets of auxiliary contact membersare progressively included in and excluded from the circuit so thatarcing at the separable main current carrying members of the switch isprevented both on switch opening and switch closing operations.

The supporting frame and its associated parts is relatively narrow aswill be seen from an inspection of Fig. 2. Thus, a number of theseframes can be placed side by side and connected in series withoututilizing an undue amount of space so that a large number of sets ofcontact members can be arranged in series, thereby to interruptsuccessfully a high voltage circuit upon the occurrence oi the firstcurrent zero after all of the contact members have separated.

While the invention has been described as incorporated in a switchhaving so many sets of serially-connected contact members that thepotential across the contact members of any one set is kept belowapproximately two hundred volts, it is apparent that the invention canbe incorporated in any switch having a large number ofserially-connected points of circuit-interruption, regardless of thepotential at each point of circuit-interruption.

I claim:

1. An electric switch having a plurality of sets of separable contactmembers connected in series in the switch circuit, said separablecontact members normally engaging each other when the switch is closed,and means to effectively include said contact members in a progressivemanner in the switch circuit while said contact members are inengagement prior to the separation of the contact members.

2. In an electric switch, the combination of current carrying members, aplurality of sets of separable auxiliary contact members normallyshunting said current carrying members, said separable contact membersnormally engaging each other when the switch is closed, and means toeffectively exelude and include said auxiliary contact membersprogressively from and in said shunting relation while said contactmembers are in engagement.

3. An electric switch having separable main current carrying members, aplurality of sets of separable auxiliary contact members arranged inshunt relation with said main current carrying members, said separablecontact members normally engaging each other when the switch is closed,and switch operating mechanism including means to progressively includesaid auxiliary contact members in effective shunting relation with saidmain current carrying members while said contact members are inengagement and thereafter to separate said main current carryingmembers.

4. An electric switch having a plurality of sets of separable contactmembers adapted to be connected in series in the switch circuit, saidseparable contact members normally engaging each other when the switchis closed, and switch operating mechanism including means normallyexcluding said contact members from the switch circuit while saidcontact members are in engagement, and means to include said: contactmembers in a progressive manner in the switch circuit.

5. An electric switch having a plurality of sets of separable contactmembers adapted to be connected in series in the switch circuit, saidseparable contact members normally engaging each other when the switchis closed and switch operating mechanism including means normallyexcluding said contact members from the switch circuit while saidcontact members are in engagement, means to include said contact membersin a progressive manner in the switch circuit, and means thereafter toseparate said contact members.

6. An electric switch including a plurality of sets of separable contactmembers adapt ed to be included in series in the switch circuit, saidseparable contact members normally engaging each other when the switchis closed, means progressively engageable with said contact members toinclude them progressively in the circuit prior to their separationwhile said contact members are in engagement, and means thereafter toseparate the contact members.

7. An electric switch having a plurality of sets of electric contactmembers adapted to be connected in series in the switch circuit, saidseparable contact members normally engaging each other when the switchis closed, connecting means which are movable in a progressi e manner toinclude said contact members progressively in series in the circuitwhile said contact members are in engagement, and means thereafter toseparate said contact members.

8. An electric switch having a plurality of sets of separable contactmembers adapted to be connected in series in the switch circuit, saidseparable contact members normally engaging each other when the switchis closed and means to include said contact members progressively in andalso to exclude them progressively from the switch circuit including aconducting rocker having means to rock upon said contact members in aprogressive manner from one to another while said contact members are inengagement.

9. An electric switch including sets of stationary and movable contactmembers, the movable contact members being arranged in a straight line,and means to include said contact members in a progressive manner in theswitch circuit, including a curved conducting rocker, and means to causeit to rock progres- 111g means which connects t sively in engagementwith said stationary contact-members from one end to the other endof'the line. 1

10. An electric switch having maincurrent carryingv members, a pluralityof sets of separable auxiliary contact members, means establishing anauxiliary circuit around said main current, carrying members whichexcludes atleast the major part of said sets of auxiliary contactmembers, and means to operate the aforesaid means to include saidcontact'members in a progressive manner in the switch circuit and thento separate said maincurrent carrying members and thereafter theauxiliary contact members.

' 11; An electric switch having a plurality of sets ofseparable contactmembers, bridghem'in series in a progressive manner, operating means forsaid bridging means, and separate operating means for said contactmembers.

12-. An electric switch havinga plurality of sets of separable Contactmembers, bridging means which connects them in series in a'progressivemanner, operating means for said bridging means, separate operatingmeans for said contact members, and operating mechanism for the twoaforesaid means including means'to operate-them in succes- 'sion.

13. An electric switch including a frame having a pair'oi verticalinsulating members, sets'oi' spacedst'ationary contact members carriedby'said vertical members, movable supports carried by said aforesaidframe, sets of movable contact'mel'nbers carried by said movablesupports and cooperating with said stationary contact members, operatingmechanism to move said movable supports toward and away from each othersimultane 'ously, contact-bridging mechanism including rockers,operating mechanism for said rockers arranged to move them progressivelyintoengagement with said contact members, and means including saidrockers connecting said sets of contact members in series.

In'testimony whereof, I have signed my name to this specification. i

' CHESTER D; AINSVVORTH;

separable

